Ok so we have the first portion. We need to do cross multiplication first. So that would be 20(2x - 9) and 10(9)
So
20(2x - 9)=90
40x - 180=90
Then add 180 to itself then to 90
40x=270
X=6.75
Now let’s set the next one up knowing what we know from the previous one.
18(3x + 4)= 12(15)
54x + 72=180
Subtract 72 from it’s self and 180
54x=108
X=2
