5 \(\times\) x\(^1\) + 5 \(\times\) x\(^0\) + 5 \(\times\) x\(^1\) + 2 \(\times\) x\(^0\) = 77

(change all  to base 10)
5x + 5 + 5x + 2 = 77
10x + 7 = 77
10x = 77-7
10x = 70
x = 70/10
x = 7