Answer:
-27
Step-by-step explanation:
9(4x – 15)
Substitute 3 for x
9((4)(3) - 15)
Multiply (4)(3) = 12
9 ( 12 - 15 )
Subtract 12 - 15 = -3
9(-3)
Multiply 9(-3) = -27
Answer:
60.1
Step-by-step explanation:
Just get 72.60 and subtract 12.50
7x / 8 = 21
7x = 8*21
x = 24
Try this:
1) note that weight of pure antifreeze before mixing and after mixing is the same. So, if 'x' is weight of pure antifreeze in 50% solution, it is possible to make up equation before mixing: 0.5x+0.2*90.
2) there are 0.2*90=18 gal. of pure antifreeze in the 20% solution. If 'x' gal. is the weight of pure antifreeze in 50% sol. and 18 gal. is the weight of pure antifreeze in 20% sol., it is possible to make up an equation after mixing: 0.4(x+18).
3) using the both parts: 0.5x+0.2*90=0.4(x+18) ⇒ x=54 gal. of <u>pure</u> weight.
4) to find 50% solution of 54 gal. pure weight just 54:0.5=108 gal.
Answer: 108 gal.
