Question

Please help me l don’t understand

Answer 1

a. Let $d$ be the number of daytime calls Eshwa makes, and $e$ the number of evening calls. Then the cost $C$ (in pence) of making $d+e$ calls is

$C = \boxed{50d + 40e}$

b. £1 = 100p, so the cost $C'$ (in £) is 1/100 of the cost found in part (a),

$C' = \dfrac{50d + 40e}{100} = \boxed{\dfrac d2 + \dfrac{2e}5}$

c. If Eshwa makes 30 of each type of call in a month, then the total cost (in £) is

$C' = \dfrac{30}2 + \dfrac{2\cdot30}5 = \boxed{27}$

c2. If Eshwa makes 20 daytime calls and 50 evening calls, then the total cost (in £) is

$C' = \dfrac{20}2 + \dfrac{2\cdot50}5 = \boxed{30}$

d. Let $e=40$ and $C'=42$. Solve for $d$.

$42 = \dfrac d2 + \dfrac{2\cdot40}5$

$42 = \dfrac d2 + 16$

$\dfrac d2 = 26$

$d = \boxed{52}$