Answer:
x = 31
Step-by-step explanation:
AC=BD
3x+7 = 131-x
Subtract 7 from both sides
3x = 124-x
Add x to 3x
4x = 124
Divide by 4
Check:
3(31)+7 = 131 - 31
Mulitply 3 times 31 / subtract 131 and 31
93+7 = 100
Add 93 to 7
100 = 100
