Question 906799
a+b=21,
0.07*a+0.04*b=0.06*21
a=21-b
0.07*(21-b)+0.04*b=1.26
1.47-0.07b+0.04*b=1.26
-0.03*b=-0.21
b=7
a=21-b
a=14  gal at 7%
b=7  gal at 4%
check
0.07*14+0.04*7=0.06*21
0.98+0.28=1.26
1.26=1.26
ok