F(x)=5x-20 what value could be substituted for x to have a solution of 30

Idont get this question can someone me solve it? ** the distance light travels in one second (1 light second) is about 1.86 ×10^5 mi. saturn is about 475 light-seconds from the sun. about how many miles from the sun is saturn..my guess is 8.83* 10^7 you so much

Can someone check my answer? you : )

How many real and imaginary solutions does the equation x^2-3x=-2x-7 have?