Write the value of a in terms of b if the line joining (b,20) and (4,a) has a slope of −5

Answer 1

(a - 20) / (4 - b) = -5

Answer 2

so
a - 20 = -20 + 5 b
a = 5 b

Answer 3

check
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(b , 20 ) and ( 4 , 5 b )
(5b - 20) / ( 4 - b) = 5 (b-4) / (4-b) = = -5 sure enough

Answer 4

thanks everyone!

Answer 5

You are welcome.