Question

the length L of a spring is given by L=(3/4)F + 5 where F is applied force. What force F will produce a length of 8?

Answer 1

L=8
F - searched force

$L=\frac{3}{4}*F+5$
$8=\frac{3}{4}*F+5$
$8-5=\frac{3}{4}*F|*\frac{4}{3}$
$3*\frac{4}{3}=F$
F=4