Ruby and her friends are going into a restaurant. How much would it cost to buy 3
1 answer:
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Answer:
see explanation
Step-by-step explanation:
(a)
y = - bx
substitute y = 6 , x = 1 into the equation
6 = a - b → (1)
substitute y = 0 , x = 2 into the equation
0 = - 2b ( multiply through by 2 to clear the fraction )
0 = a - 4b → (2)
multiply (1) by - 4
- 24 = - 4a + 4b → (3)
add (2) and (3) term by term to eliminate b
- 24 = - 3a + 0
- 24 = - 3a ( divide both sides by - 3 )
8 = a
substitute a = 8 into (1) and solve for b
6 = 8 - b ( subtract 8 from both sides )
- 2 = - b ( multiply both sides by - 1 )
2 = b
Then a = 8 and b = 2
(b)
when x = 4
y = - 2(2) = 2 - 4 = - 2