Question 280516
x+97/(y+1)=90 cross multiply.
x+97=90y+90
x+73/(y+1)=87 cross multiply.
x+73=87y+87 subtract the other equation.
-(x+97=90y+90)
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-24=-3y-3
-3y=-24+3
-3y=-21
y=-21/-3
y=7 total tests previously taken befre the 90 or 73 grade test.