Answer:
2x - 3
Step-by-step explanation:
The missing side is the value of the perimeter subtract the sum of the 2 given sides, that is
? = 10x + 1 - (5x - 2 + 3x + 6)
= 10x + 1 - (8x + 4) ← distribute parenthesis by - 1
= 10x + 1 - 8x - 4 ← collect like terms
= 2x - 3
