Subtract 10 and collect terms to get the variable term by itself on the left.
... 4c = 24
Divide by the coefficient of the variable, 4.
... c = 6
The appropriate choice is the second one:
... 6
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You don't actually have to sove the equation to find the right answer. You just need to see which answer works.
-6: 5(-6) -(-6) +10 = -14 ≠ 34
6: 5(6) -(6) +10 = 34 . . . . . . . this answer works (you can stop here)
11: 5(11) -(11) +10 = 54 ≠ 34
-11: 5(-11) -(-11) +10 = -34 ≠ 34
