The correct answer is d hope i could help
3x+4y=23
2y-x= -19/ multiply -2
4y + 3x = 23
-4y - 2x = 38
_______________
X = 61
2y - x = -19
2y - 61 = -19
2y = 61 -19
2y = 42
Y = 21
Exactly 80 liters of 20% are needed.
Let quantity of 20% alcohol solution be added : x liters
Here is the work:
> x*20% + 40 * 50% = (x+40) * 30%
> x*0.2 + 40*0.5 = (x+40)*0.3 ..(converting percentages into decimal)
> 0.2x + 20 = 0.3x + 12
> 20-12 = 0.3x - 0.2x (Rearranging similar terms)
> 8 = 0.1 x
Hence x = 8/0.1
Ans 80 Litres
Microwaves cause internal heating of the body tissue