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The expression (2x+5) has the same value as y, and so we can use (2x+5) instead of y in the second equation. This means that we are now just dealing with one variable (x) instead of two (x and y). If we m...

a² = 3² = 9, b² = 4² = 16, a² + b² = 3² + 4² = 25, c² = 25, c = 5

Estimate, so: 900 litres, and 20 litres per day. 900/20 = 45 However, any estimation that results in an answer between 44-56 is acceptable.

• multiply everything by 5, so you get 6y - 30 = 10x + 12 - add 30 to both sides, so you get 6y = 10x + 42 - divide everything by 6, so you have y = (10/6)x + (42/6) - simplify, y= (5/3)x + 7 - this i...

First of all we want to expand the brackets out. We do this by mulitplying 4 by each number in the bracket. This then gives us 14-x = 4+4x. We then want to get all the x's on one side and the numbers on t...