Answer:
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Answer:Mark Is 9 years old; Christine is 5 years old
Step-by-step explanation:
Present age
LET mark age be x
Christine be x-4 yrs
In 3 yrs Time
Mark will be x+3 yrs old
Christine will be (x -4 +3) = x-1 years old
Also, In 3 years time
Christine = 2/3 Mark
such that
x-1 = 2/3(x+3)
x -1= 2x+6 / 3
3x -3= 2x+6
3X--2X = 6+3
=X=9
Mark Is 9 years old
Christine is x -4 = 9-4=5 years old
We have two points so we can find the gradient using y1-y2/x1-x2
gradient = 21-27/2-8
= 1
we know the form for any linear equation is y = mx + c
we have m and a point so we can substitute in point (2,21) to find c
21 = 1 x 2 + c
c = 19
therefore, the equation is y = x + 19
