Begin by creating a system of equations: let 'a' represent the amount Mary earns per student, and 'b' denote her fixed amount. The equations are 90=15a+b (subtracting the lower from the upper equation) and 62=8a+b. From these, we have 90-62=28, leading to 15a-8a=7a, and b cancels itself out. This gives us 7a=28, resulting in a=4. Substituting 'a' into 62=8a+b reveals b=30. Since Lisa earns half of Mary's base, her fixed amount is 15, but she makes twice as much per student, bringing her rate to 8 per student. Thus, we can formulate: m=4c+30 for Mary's earnings, and l=8c+15 for Lisa's. Setting c=20 results in m=110 and l=175, showing that Lisa makes more when teaching a class of 20 students. I trust this information helps.
(a) When rounded, 14.90 becomes 15, and 1.25 rounds to 1, so 15-1 results in $14.
(b) My estimate may be higher as I had to round the larger number up while the smaller number was rounded down, creating a greater difference between the estimate and the actual amount.
(c) The computation yields 14.90-1.25=13.65, thus Pedro has $13.65 remaining in his wallet. The difference between the estimate and the actual figure is 14-13.65=0.35, indicating a $0.35 discrepancy between the estimate and the actual remaining amount in Pedro's wallet.
4.2x - 1.4y = 2.1
-1.4y = 2.1 - 4.2x
y = \frac{2.1 - 4.2x}{-1.4}
y = 3x - 1.5 <==
