Answer:
D (7a-3)/4
Step-by-step explanation:
7a – 4b = 3
Subtract 7a from each side
7a-7a – 4b = 3-7a
-4b = 3 -7a
Divide by -4
-4b/-4 = (3-7a)/-4
b = (7a-3)/4
In constructing the equation, you need to know the following:
1. What don't we know? How many minutes you must talk to have the same cost for both calling plans. So, let x be the number of minutes.
2. What do we know? Plan 1 charges $17.50 per month plus $0.17 per minute used and Plan 2 charges $32 per month plus $0.07 per minute used.
So the equation must look like this: 17.50 + .17x = 32 + 0.07x
Solving the equation:
1. Multiply both sides by 100
(100) 17.5 + .17x = 32 + 0.07x (100)
1750 + 17x = 3200 + 7x
2. Subtract 1750 from both sides
1750 + 17x - 1750 = 3200 + 7x - 1750
17x = 7x +1450
3. Subtract 7x from both sudes
17x - 7x = 7x + 1450 - 7x
10x = 1450
4. Divide both sides by 100
10x / 10 = 1450/10
x= 145 minutes
145 minutes is the number of minutes you must talk to have the same cost for both calling plans.
<span>Expressing in simplest radical form just means simplifying a radical so that there are no more square roots, cube roots, 4th roots, etc left to find. It also means removing any radicals in the denominator of a fraction.</span>
