CPhill

40.80/4 and 81.60/8   are equal ratios

So

40.80 / 4   =  $10.20 per hour

Compare

2.79/2   and  2.98/3

Whichever is less is the better deal......

(8+ 1/2 )  - (3 + 3/4) =

(17/2) - (15/4)   =   get a common denominator = 4

(34/4) - (15/4)  =

19/4 km =  4 + 3/4  km

7(1 + .045)^5 = $8.72

The sequence progression is

30(-1/3)^n-1    for n = 1, 2, 3, 4......

So the next one would be

30(-1/3)^5-1  = 30(-1/3)⁴   = 30(1/81) = 30/81 = 10/27

And I'll let you do the next two....

 7x < 84 divide both sides by 7

x < 12

And that's it....

To find the hypotenuse, square each leg and add together

So

150^2 + 120^2 = 36900

The hypotenuse will be the square root of this

√36900 = about 192.1

Looks like you were pretty close....!!!

So we have

log₁₅ (1/√15)  =

log₁₅ 15^-1/2 =

(-1/2)log₁₅ 15 =

-1/2

Using dimensional analysis to convert km to miles, we have

100km x  1000m/ 1 km x 39.37in / 1m x 1ft / 12 in x 1 mile / 5280 ft = 62.136m/hr

Note the cycle

9^1 = 9

9^2 = 81

9^3 = 729

9^4 =  6561     and this pattern repeats for every "block" of 4 powers

Note that 40 is evenly divisible by 4, so 9^40 has a "ones" digit that completes this cycle. So....9^40  ends in a "1"