Question

Difficulty: HardLinear Equations in One and Two Variables

A corporate advisory firm executes two types of client projects: Type A and Type B. Each Type A project requires xx hours of financial modeling and yy hours of executive reporting. Each Type B project requires x+3x + 3 hours of financial modeling and 2y22y - 2 hours of executive reporting. During the first quarter, the firm completed 6 Type A projects and 4 Type B projects. If the total time spent on financial modeling across all 10 projects was 72 hours and the total time spent on executive reporting was 62 hours, what is the value of 3x+4y3x + 4y?

Answer: 38

Answer

The value of 3x+4y3x + 4y is 38.
Setting up total financial modeling hours gives 6x+4(x+3)=726x + 4(x + 3) = 72, which yields x=6x = 6. Setting up total executive reporting hours gives 6y+4(2y2)=626y + 4(2y - 2) = 62, which yields y=5y = 5. Substituting these values into 3x+4y3x + 4y yields 3(6)+4(5)=383(6) + 4(5) = 38.

Step-by-Step Solution

1
Formulate and solve the linear equation for financial modeling hours.
x=6x = 6
6 Type A projects take 6x6x hours and 4 Type B projects take 4(x+3)4(x + 3) hours. Summing them yields 6x+4x+12=726x + 4x + 12 = 72, which simplifies to 10x=6010x = 60, giving x=6x = 6.
2
Formulate and solve the linear equation for executive reporting hours.
y=5y = 5
6 Type A projects take 6y6y hours and 4 Type B projects take 4(2y2)4(2y - 2) hours. Summing them yields 6y+8y8=626y + 8y - 8 = 62, which simplifies to 14y=7014y = 70, giving y=5y = 5.
3
Substitute x=6x = 6 and y=5y = 5 into the targeted expression 3x+4y3x + 4y.
38
3(6)+4(5)=18+20=383(6) + 4(5) = 18 + 20 = 38.

Key Concept

Linear Equations in One and Two Variables
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