How do i find the mistake the student did?

Step-by-step explanation:

What he did at the end of the given equations is solve for x in x + 8y= 21

x = 21 - 8y                Substitute that result in the top equation.

7(21 - 8y) + 5y = 14  is the correct step To continue Remove the brackets

147 - 56y + 5y = 14   Combine

147 - 51y = 14             Add 51y to both sides.

147 = 51y + 14            Subtract 14 from both sides.

133 = 51y                   divide by 51

y = 2.61 rounded.

The incorrect step is underlined and italicized.

walter needs to make at least 5 more cookies but no more than 40. 5 ≤ x ≤ 40

step-by-step explanation:

20 ≤ x + 15 ≤ 55

subtract 15 from all parts

20-15 ≤ x + 15-15 ≤ 55-15

5 ≤ x ≤ 40

this means how many more cookies he has to make

walter needs to make at least 5 more cookies, but no more than 40 cookies; 5 ≤ x ≤ 40

if a = 1,   and b = 2, then the answer is 47.99999999. if you round that to the nearest whole number, the answer is 48.