Answer:
21/20
Step-by-step explanation:
a) One hour is equivalent to 60 minutes.
So we can multiply 50 minutes by the fraction
, so we could convert 50 minutes to hours.
It is:

If we simplify the fraction, we have:

b) In order to express the turtle's speed in miles per hour, we have to divide
by 
So:

We simplify the expression by multiplying 7 mile by 6 and 8 by 5 hours:

The "rule of 72" says that the doubling time in years is approximately 72 divided by the interest rate in percent. To make the money grow by a factor of 4 requires that it double twice, so will take twice as long as the period to double once.
2×72/11.3 ≈ 12.7 . . . . years
_____
The "rule of 72" is an approximation. The actual quadrupling time for this interest rate and compounding is about 12.6 years. (The actual product of doubling time and nominal interest rate is about 71.25.)
Answer:
Which expression is equivalent to RootIndex 3 StartRoot 64 a Superscript 6 Baseline b Superscript 7 Baseline c Superscript 9 Baseline EndRoot?
2 a b c squared (RootIndex 3 StartRoot 4 a squared b cubed c EndRoot)
4 a squared b squared c cubed (RootIndex 3 StartRoot b EndRoot)
8 a cubed b cubed c Superscript 4 Baseline (RootIndex 3 StartRoot b c EndRoot)
8 a squared b squared c cubed (RootIndex 3 StartRoot b EndRoot)
Triangles = 180 so you’d use the equation ABC (60) + BAC (50) + ACB (x) = 180
Which equals out to ACB= 79