Mrs. Wadley bought 15 white shirts and 3 black shirts.
Step-by-step explanation:
Cost of one white shirt = $4
Cost of one black shirt = $5
Students in class = 18
Money spent on shirts = $75
Let,
white shirts = x
black shirts = y
According to given statement;
x+y=18 Eqn 1
4x+5y=75 Eqn 2
Multiplying Eqn 1 by 5;
[tex]5(x+y=18)\\5x+5y=90\ \ \ \ Eqn\ 3[/tex]
Subtracting Eqn 2 from Eqn 3;
[tex](5x+5y)-(4x+5y)=90-75\\5x+5y-4x-5y=15\\x=15[/tex]
Putting x=4 in Eqn 1
[tex]15+y=18\\y=18-15\\y=3[/tex]
Mrs. Wadley bought 15 white shirts and 3 black shirts.
Keywords: linear equation, subtraction
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