Question 1189846
let x = the amount of solution in the first brand.
let y = the amount of solution in the second brand.


you have two equations that need to be solved simultaneously.
they are:


x + y = 50
.7 * x + .95 * y = .75 * 50


multiply both sides of the first equation by .7 and lease the second equation as is to get:
.7 * x + .7 * y = .7 * 50
.7 * x + .95 * y = .75 * 50


simplify the right side of each equation to get:
.7 * x + .7 * y = 35
.7 * x + .95 * y = 37.5


subtract the first equation from the second to get:
.25 * y = 2.5


solve for y to get:
y = 10


that means x = 40 because 40 + 10 = 50


confirm the solution is correct by replacing x with 40 and y with 10 in both original equations.


x + y = 50 becomes 40 + 10 = 50 which becomes 50 = 50
.7 * x + .95 * y becomes .7 * 40 + .95 * 10 which becomes 28 + 9.5 which becomes 37.5


this confirms the solution is correct.
the solution is 40 gallons of the first brand and 10 gallons of the second brand is required.