Answer:
C
Step-by-step explanation:
15 times 2 is 30
1 times 2 is 2
Proportinal
Hope this helps
Answer:
The value of T₂₀ - T₁₅ is <u>-20</u>.
Step-by-step explanation:
<u>Given</u> :
<u>To</u><u> </u><u>Find</u> :
<u>Using Formula</u> :
General term of an A.P.

- >> Tₙ = nᵗʰ term
- >> a = first term
- >> n = no. of terms
- >> d = common difference
<u>Solution</u> :
Firstly finding the A.P of T₂₀ by substituting the values in the formula :






Hence, the value of T₂₀ is a + 19d.

Secondly, finding the A.P of T₁₅ by substituting the values in the formula :






Hence, the value of T₁₅ is a + 14d

Now, finding the difference between T₂₀ - T₁₅ :









Hence, the value of T₂₀ - T₁₅ is -20.

We need to call for x minute
+ Phone Company A charges a monthly fee of $42.50, and $0.02 for each minute talk time. So we have to spend: <span>$42.50+ $0.02x
+ </span>Phone company B charges a monthly fee of $25.00, and $0.09 for each minute of talk time. So we have to spend: <span>$25.00+ $0.09x
We solve for x: </span>$42.50+ $0.02x> <span>$25.00+ $0.09x
or </span>$42.50- $25.00 > $0.09x- <span>$0.02x
and we have $0.07x<$27.50
or x< 27.50:0.07 and x< 393.86
The answer is:
If we have to call much time, at least 394 minutes, we should choose A
If not, choose B</span>