3x+7=-15
-7=-7
3x=-22
you cannot get the number only if it has a decimal
4/x+9 = 9/x+5.... x= -61/5 or -12 1/5
try using the app Photomath, it’s really useful
$2.35 to buy lunch at school for 9 days
so you take 2.35 and multiply it by 9
you get 21.15
2.35 x 9 = 21.15
therefore he spent 21.15 in 9 days
It is 500% because it is increased by 5 times.