Diketahui f(x)=-2x+15. Jika f(a)=9, maka nilai a adalah...

f(x) = -2x + 15
f(a) = 9
-2a + 15 = 9
-2a = 9 - 15
-2a = -6
a = 3

f(a)= -2a+15=9
=>-2a =9-15
=> -2a = -6
=> a = -6/-2
=> a = 3

*semoga bermanfaat