As you may have noticed the formula for gradient is
(Change in <span>yy</span>)/(change in <span>xx</span>)
Therefore
<span><span>(−5−15)/(−8−−2)</span><span>(−5−15)/(−8−−2)</span></span>
<span><span>=−20/−6</span><span>=−20/−6</span></span>
<span><span>=10/3</span></span>
2 times x and -5
2x-10-6x=-22
Then do 2x +-6x
-4x-10=-22
Next, 10 + -22
-4x=-12
Divide the 12 by 4
X=3
Greatest proportion = Glass c 12.75%
Glass a is 3/25 = 12% and Glass b is 1/8 = 12.5%
If putting 5.2 and 4.5 in fraction form, her error must have been timing 3 by 3 to 5.2 and 4.5 as a fraction. Meaning that 5.5 and 4.8 is wrong