Recall the logarithm rules :
a^y = x is the same as log_a x = y
In this case,
a = 18
y = r - 10
x = 93
So,
18^ (r-10) = 93
is the same as
log_18 93 = r - 10
Solve for r to get :
10 + log_18 93 = r
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Step-by-step explanation:
Let x be the miles Kenyon ran on tuesday
Let y be the miles Kenyon ran on thursday
Given,
Mon + Tues + Wed + Thu = 8mi

also given,

Now we have x + y = 5.2 as equation 1 and -x + y = 0.4 as equation 2
Using equation 1,

Substitute this equation into equation 2.

Substitute y = 2.8 into equation 1.

Therefore Kenyon ran 2.4 miles on tuesday, and ran 2.8 miles on thursday.
1) Sundaes - $2 ; Banana Splits - $3
3x + 2(x+8) = 156
3x + 2x + 16 = 156
5x = 156 - 16
5x = 140
x = 28 banana split ; x + 8 = 28 + 8 = 36 sundaes
2) Palanzio's = 6.80 + 0.90x ; Guido's = 7.30 + 0.65x
6.80 + 0.90x = 7.30 + 0.65x
0.90x - 0.65x = 7.30 - 6.80
0.25x = 0.50
x = 2 number of toppings.
6.80 + 0.90x = 7.30 + 0.65x
6.80 + 0.90(2) = 7.30 + 0.65(2)
6.80 + 1.80 = 7.30 + 1.30
8.60 = 8.60
3) 6x - y = 4 ; y = 4x + 2
6x - (4x+2) = 4
6x - 4x - 2 = 4
2x = 4 + 2
2x = 6
x = 6/2
x = 3
y = 4x + 2
y = 4(3) + 2
y = 12 + 2
y = 14
6x - y = 4
6(3) - 14 = 4
18 - 14 = 4
4 = 4