Answer:
C. x=10
Step-by-step explanation:
Using the Pythagorean Theorem, you know that 7²+s²=(√74)², I'm using the variable s so we don't get confused with the other x variable.
Square root the numbers you can: 49+s²=74
Subtract 49 from both sides of the equation to isolate the variable: s²=25
Square root both sides to find the value of s: s=5
S is half of the value of x, so double s to get your answer, 10