x=child y=adult
x+y=142 --number of tickets
5.90x+9.30y=1031.60 --total sale
for this one, use the substitution method
since youre finding the # of adult tickets sold, isolate the x-value on the first equation
x=-y+142
plug -y+142 into all x values in the second equation
5.90(-y+142)+9.30y=1031.60
-5.90y+837.80+9.30y=1031.60 --distribute
3.40y+837.80=1031.60 --combine like terms
3.40y=193.80 --subtract across the sign
y=57 --divide across the sign
there were 57 adult tickets sold
