Question

Robinson Wholesale Company paid $1370 for 500 items. Later they bought 800 items for $1730. Assume that the cost is a linear function of the number of items. Write the

equation. (Let y represent the amount paid and x represent the number of items purchased.)

Answer 1

y = 1.2x + 770

Explanation:

y = m*x + b

Equation One

y = mx + b

1370 = m*500 + b

Equation Two

y = mx + b

1730 = m*800 + b

Solution

1730 = 800*m + b

1370 = 500*m + b Subtract. The b's cancel

360 = 300 * m Divide both sides by 300

360/300 = m

1.2 = m

Now use the second equation to solve for b

y = 1730

x = 800

1730 = 1.2*800 + b

1730 = 960 + b Subtract 960 from both sides

b = 770