Explanation:
what is so difficult for you ?
r - 7 > -10
the only thing that keeps us from a direct answer is the "- 7" on the side of r.
to get rid of it, we have simply to add 7. but to kero the inequality balance unchanged, we need to do this on both sides :
r - 7 + 7 > -10 + 7
r > -3
that's really all.