Simultaneous equations 2x + y = 21 x - y = 6

Step-by-step explanation:

this is substitution method

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

a) 0

step-by-step explanation:

i^413 x i^0 = 0 as any number multiplied by a zero is

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