Amanda invests $5,000 in a CD at an annual interest rate of 2%. What will her investment be
worth at the end of three years?

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4

thats not a system of equations, that is a solution

6x = 48

i hope this . 6 cards each and a total of $48. dvide each side by 6 and you will have your answer.