You buy the sandwiches at subway for $30 that included 6 tuna sandwiches and 6 turkey sandwiches
Let x be the price of tuna sandwiches
and y be the price of turkey sandwiches
6x + 6y = 30
Divide both sides by 6
x + y = 5 ---------- equation 1
you buy more sandwiches and buy 4 tuna sandwiches and 8 turkey sandwiches for $30.60.
4x + 8y = 30.60 ---------equation 2
x + y = 5
so y = 5 -x
Now plug in 5-x for y in second equation
4x + 8y = 30.60
4x + 8(5 - x) = 30.60
4x + 40 - 8x = 30.60
-4x + 40 = 30.60
Subtract 40 on both sides
-4x = -9.4
divide both sides by -4
x = 2.35
We know y = 5 -x
y = 5 - 2.35 = 2.65
the price of tuna sandwiches= $2.35
the price of turkey sandwiches= $2.65