Israel and carlos were both eating at the same restaurant. israel bought 4 hamburgers and 2 orders of fries for $9.74. carlos bought 12 hamburgers and one order of fries for $22.77. if tashiana buys 3 hamburgers and one order of fries at the same restaurant, how much will be her total bill? a.) $6.66 b.) $6.47 c.) $5.66 d.) $5.37

Let
x-----------> cost of one hamburger
y-----------> cost of one order of fries

we know that
4x+2y=9.74--------------> equation 1
12x+y=22.77-----------> y=22.77-12x-----------> equation 2

using a graph tool---------> calculate the equations system
see the attached figure

the solution is 
x=1.79
y=1.29

the cost of one hamburger is $1.79
the  cost of one orders of fries is $1.29

If Tashiana buys 3 hamburgers and one order of fries 
3*1.79+1.29---------> $6.66

the answer is $6.66

I’m not sure how this works