Answer is 8
to do the problem...
First add ten to the negative 10 and the 14. (this cancels out the negative ten in the original problem) (the number 14 plus 10 equals 24)
Secondly, divide by three on both sides.
Third, the number 24 divided by 3 equals 8.
Ratio of A to B is 7:5...
so if there was 295 mL of compound B...
7 / 5 = a / 295
cross multiply
(5)(a) = (295)(7)
5a = 2065
a = 2065/5
a = 413 .... so 413 mL of compound A would be used
for a total solution of (295 + 413) = 708 mL solution <===
Let's solve this by substitution.
y is given by the 2nd eqn as y = (1/3)x + 7. Subst. (1/3)x + 7 into the first eqn as a replacement for y: x + 9( (1/3)x + 7) = 3.
clear out fractions by mult. all 3 terms by 3: 3x + 9x + 63 = 3
Combine like terms: 12x = -60. Then x = -5
Find y by subst. -5 for x in the 2nd equation: y = (1/3)(-5) + 7
= -5/3 + 35/3 = 30/3 = 10.
Thus, the solution (x,y) of this system is (-5,10).
