"find the indicated function values"i just want to know how to do one of them (a, b, or c)

A)   f(-10)

meaning x = -10

the first subfunction applies only below that, namely x < -10.

the second subfunction does contain -10 in it since -10 ⩽ x ⩽ 10, so we use that one then,
 
x = -10, thus x² is (-10)², or 100.

b)    f(10)

x = 10.

that will also be the second subfunction, since it's the one that contains 10, thus,

x = 10, x² is (10)² or 100.

c)  f(11)

x = 11.

well, is not the second subfunction, since its domain goes up to 10, x⩽10.

looking at the third subfunction, that includes 11, since x > 10, thus,

x = 11,

(11)² + 10

121 + 10

131.

300b(x) is graphed by the functio