If we put a radio telescope on Mars and use it in array with earth radio telescopes, how much will we able to see? Will it allow us to see planets, like we do with black hole?
This is answering a somewhat different question, but one that seems implied by this one:
To put a radio telescope on Mars requires the capability to launch the radio telescope to Mars, and then to land it on Mars and then deploy it there. This will be considerably more costly and difficult than just launching it into solar orbit...after all, the first step of getting it to Mars is to do just that, and it doesn't even need to be an orbit that reaches all the way to Mars.
A telescope on Mars would have less gravity to deal with on Earth, but would still have gravity to deal with. This means it will have to be far more heavily built than a telescope designed to operate in microgravity. So not only is it more expensive per-kg to get it where it needs to go, you have more kg to send there.
Also, it would have to deal with Martian dust, which is electrostatically charged and periodically carried aloft in large dust storms, and with the Martian ionosphere, which will block certain bands and cause interference just like Earth's.
Additionally, a telescope on Mars will be restricted to viewing a fraction of the sky determined by its location on Mars and the rotation of Mars. It would only be able to make uninterrupted observations near the poles of Mars, and then only if located close enough to the poles, which would raise issues with the winter temperature extremes and power issues with long high-latitude winter nights.
That last issue is a major problem for interferometry, because the parts of the sky the Mars telescope could see are not necessarily the parts its Earth counterpart could see. Also, Earth and Mars gets you two nodes with a long baseline in only one direction, which varies depending on their relative orbital locations. In orbit you could have a 3D array with as many nodes as you like (though they would be most easily placed in a ring around the sun in near-Earth orbits). This gives you far more capability: two nodes would allow you to do things like measure diameters and distances, and maybe distinguish close objects if they are in the right part of the sky and separated in the right direction. An 2D or 3D orbital array would allow you to actually image things.
To balance that list of cons, we have...what? Eventually, perhaps people will be living there who can handle construction, repair, and upgrades, but anywhere with human occupation will also have human interference, and this advantage doesn't actually exist yet. What else? There's really nothing.
(Notably, most of these disadvantages are shared on the moon. The only real difference is that the moon has no ionosphere, and can to some extent serve as a shield against interference from the solar wind, which is important if you're making certain very specific types of observations.)