well there are two answers for that.
1: you need 120 ones then that will equal up to 120.
2: you could also do one 100 and 2 tens.
those are the answers that i have thought of.
-2x + 7 = 7
subtract 7 from both sides.
-2x = 0
divide both sides by -2.
x = 0
irrational, cannot