Answer:
PEMDAS parentheses exponents multiplication divide add subtract....
One solution because it only has one answer that can come out if those properties. If you add the -3 to -6 it will make it 6=12 -3x. Subtract the 12 it will be -6=-3x divide by -3 and x=2
So to find percent increase, you want to minus the difference in cost..
1.09- 0.87= .22...
now divide the difference by the original....
.22 ÷ .87 = .25287.....etc
now multiply that by 100...
.25287 × 100 = 25.287
now it says round to the nearest tenth so...
25.29% increase.
90-n=3n hope this helps you