STEP-BY-STEP SOLUTION:
Let's solve this problem step-by-step.
We will be using simultaneous equations to solve this problem.
Let's first establish the equations we will be using as displayed below:
Let x = fancy shirts
Let y = plain shirts
Equation No. 1 -
x + y = 7
Equation No. 2 -
28x + 15y = 131
To begin with, let's make ( x ) the subject in the first equation as displayed below:
Equation No. 1 -
x + y = 7
x = 7 - y
Now let's substitute the equation for ( x ) from the first equation into the second equation as displayed below:
Equation No. 2 -
28x + 15y = 131
28 ( 7 - y ) + 15y = 131
196 - 28y + 15y = 131
- 28y + 15y = 131 - 196
- 13y = - 65
y = - 65 / - 13
y = 5
From here, let's substitute the value of ( y ) from the second equation into the first equation as displayed below:
Equation No. 1 -
x = 7 - y
x = 7 - ( 5 )
x = 2
ANSWER:
x = 2
y = 5
Therefore, Kecia bought a total of 2 fancy shirts and 5 plain shirts.