You save 5 cents per ounce by using the 40 ounce jar, because if you do $5.20 divided by 40 it equals $0.13 but if you do $2.70 divided by 15 it equals $0.18 which is 5 more cents the the 40 ounce
8y^2 + 12x - 4y^2 + 24x
= 4y^2 + 36x
in 1st figure
2:1=(x+2):2
2/1=(x+2)/2
4=x+2
x=2.
Similarly in the 2nd figure
8:5=(8+3):(5+x)
8/5 = 11/ (5+x)
8(5+x) =55
40+8x=55
8x=15
x=15/8
x=1.875
Find the amount of tax money she needed to pay
7% of 17.50
=7/100 * 17.50
=122.50/100
=1.22
Find the final sales price
17.50+1.22 = 18.72