James callahan has available a 10% alcohol solution and a 60% alcohol solution. find how many liters of each solution he should mix to make 50 liters of a 40% alcohol solution?

Let
x> liters of 10% alcohol solution
y> liters of 60% alcohol solution

we know that
x+y=50> x=50-y> equation 1
0.10x+0.60y=0.40*50> 0.10x+0.60y=20> equation 2

substitute 1 in 2 
0.10*(50-y)+0.60y=20> 5-0.10y+0.60y=20
5+0.50y=20> 0.50y=15> y=30
x+y=50> x=50-30> x=20

the answer is
20 liters of 10% alcohol solution
30 liters of 60% alcohol solution

That. you would have multiple

38+105= 143, 39+104=143, and you will find then adding the numbers on opposite sides, moving inwards yields the answer 138 every time. because of this, you’re going to multiply 138 times the number of pairs, which is 34. therefore, 34*138= 4692(i’m sorry if it’s the wrong numbers, but it’s the right concept)