Question

4×[26.5-3×(X-7.9×6.3)]+4.5=89.74

Answer 1

$\displaystyle 4\cdot [26,5-3\cdot(x-7,9\cdot 6,3)]+4,5=89,74 \\ 4 \cdot [26,5-3 \cdot (x-49,77)+4,5=89,74 \\ 4 \cdot (26,5-3x+149,31)+4,5=89,74 \\ 106-12x+597,24+4,5=89,74 \\ -12x=89,74-106-597,24-4,5 \\ -12x=-618 \\ x= \frac{-618}{-12} \\ x=51,5$