Solve.
-When making a telephone call using a calling card, a call lasting 6 minutes cost $\$ 2.90$. A call lasting 15 minutes cost $\$ 6.50$. Let $y$ be the cost of making a call lasting $x$ minutes using a calling card. Write a linear equation that models the cost of a making a call lasting $x$ minutes.
A) $\mathrm { y } = 0.4 \mathrm { x } + 0.5$
B) $y = \frac { 5 } { 2 } x - \frac { 121 } { 10 }$
C) $\mathrm { y } = - 0.4 \mathrm { x } + 5.3$
D) $y = 0.4 x - 8.5$

Question

Quizplus · Accepted Answer

To find the linear equation, we first calculate the slope (m) using the two given points: (6, 2.90) and (15, 6.50). The slope $m = \frac{6.50 - 2.90}{15 - 6} = \frac{3.60}{9} = 0.4$. Then, using one of the points and the slope, we can find the y-intercept (b) using the equation $y = mx + b$. Substituting $x = 6$, $y = 2.90$, and $m = 0.4$, we get $2.90 = 0.4(6) + b$, leading to $b = 0.5$. Thus, the equation is $y = 0.4x + 0.5$.

Solve -When Making a Telephone Call Using a Calling Card $2.90\$ 2.90$2.90

Solve
-When Making a Telephone Call Using a Calling Card $\$ 2.90$