Assuming that the cost per minute is the same for both months and the plan fee is the same, you can use y=mx+b for this

y is the cost of the phone plan, x is the cost per minute and b is the start cost.

so 19.41=25x+b for the first month
and 45.65=380x+b for the second month

solve both for b you get:
19.41-25x=b and 45.65-380x=b. from this we get
19.41-25x=45.65-380x

solve for x

328x=26.24 and x=0.08

this means the cost per minute is 0.08c/min (answer A)

rewrite the equation to calculate b, and where this time, the x is the number of minutes talked.

y=0.08x+b and plug in one of the two months

45.65=0.08 * 380 + b

Solve for b and b is 15.25

so the final equation is

y=0.08x+15.25 (answer B)

5 0

3 years ago

A segment with endpoints A (2, 1) and C (4, 7) is partitioned by a point B such that AB and BC form a 3:2 ratio. Find B.

sdas [7]

$\bf ~~~~~~~~~~~~\textit{internal division of a line segment} \\\\\\ A(2,1)\qquad C(4,7)\qquad \qquad \stackrel{\textit{ratio from A to C}}{3:2} \\\\\\ \cfrac{A\underline{B}}{\underline{B} C} = \cfrac{3}{2}\implies \cfrac{A}{C} = \cfrac{3}{2}\implies 2A=3C\implies 2(2,1)=3(4,7)\\\\[-0.35em] ~\dotfill\\\\ B=\left(\frac{\textit{sum of "x" values}}{\textit{sum of ratios}}\quad ,\quad \frac{\textit{sum of "y" values}}{\textit{sum of ratios}}\right)\\\\[-0.35em] ~\dotfill$

$\bf B=\left(\cfrac{(2\cdot 2)+(3\cdot 4)}{3+2}\quad ,\quad \cfrac{(2\cdot 1)+(3\cdot 7)}{3+2}\right)\implies B=\left( \cfrac{4+12}{5}~,~\cfrac{2+21}{5} \right) \\\\\\ B=\left(\cfrac{16}{5}~~,~~\cfrac{23}{5} \right)\implies B=\left( 3\frac{1}{5}~~,~~4\frac{3}{5} \right)$

8 0

3 years ago

Read 2 more answers