Answer:
21.2
Step-by-step explanation:
[tex]x\times(x+ 28) = 20\times (20+32)\\\\x^2+28x-1040=0\\\\\ x=\dfrac{-28\pm\sqrt{28^2-4\cdot1\cdot(-1040)}}{2\cdot1}= \dfrac{-28\pm\sqrt{4944}}{2}\\\\x\approx21.2\quad or\quad x\approx-49.2[/tex]
x has to be >0 so the answer is 21.2
