You have already done half of it. Now substitute for x1 = 4 and y = 5
y - 5 = 6/7(x - 4)
Multiply everything by 7 to remove fractions
7y - 35 = 6(x - 4)
7y - 35 = 6x - 24
-6x + 7y = -24 + 35
-6x + 7y = 11
Some people prefer a positive number in front of x so multiply by -1
6x - 7y = -11
You can check the answer by testing it works for both of the original points
6x4 - 7x5 = 24 - 35 = -11 true
6x-3 - 7x-1 = -18 - -7 = -11 true
1) -3x-4y=10 ==> - 3x = 10+4y ===> 3x= -10-4y==> x=(-10-4y)/3
Now replace x by its value in 2)
2) -6x+y=-16 ==> - 6[( - 10- 4y)/3] + y = -16 ==> -2[(-10-4y] +y =- 16
+20+8y+y =- 16==> 9y = - 16 - 20 ==> 9y = -36 & y = - 4.
Now replace y by (- 4) in any of the 2 equations & you will find x = 2
You want to isolate the variable 'y'.

Subtract 10 to both sides:

Divide -3 to both sides:
Ok so i think you could do the leg wax, salt scrub, and the aroma bliss for $149.00 in total. Then the time would be 155 mins which would be almost 3 hours. for the time.