Answer:
Here you go :)
Step-by-step explanation:
8 ft= ___ inches
1 ft= 12 inches
8 ft= 12 x 8 inches
8 ft=96 inches
She has 96 inches, but she needs 100 inches. So she needs 4 more inches of lumber.
> multiply the second equation by 2 and add it to the first equation.
2(-6x - 7y = -10)
-12x -14y = -20
8x + 14y = 4
-12x - 14y = -20
--------------------
- 4x + 0 = - 16
x = -16/-4
x = 4
> use x = 4 in either equation to find y
8(4) + 14y = 4
32 + 14y = 4
14y = 4 - 32
14y = -28
y = -28/14
y = -2
a = amount (in oz) of solution A
b = amount of solution B
The scientist wants a mixture of 110 oz, so
a + b = 110
Solution A consists of 65% salt, so each ounce of solution A contributes 0.65 oz of salt; similarly, each ounce of B contributes 0.9 oz. The mixture is supposed to consist of 75% salt, which amounts to 0.75 * (110 oz) = 82.5 oz of salt. So
0.65 a + 0.9 b = 82.5
Solve for a and b:
b = 110 - a
0.65 a + 0.9 (110 - a) = 82.5
0.65 a + 99 - 0.9 a = 82.5
0.25 a = 16.5
a = 66 ==> b = 44