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There is a simple way of making calculations with percentages.
Say you want to subtract from a numerical value x,20%. Then multiply it with 80/100.
Say you want to add 20%.Then multiply with 120...

Many students ask how they can they find 2 unknowns,given 2 simple equations. I'll try to focus in this answer on giving students a tool which they can use to solve ANY 2 simple equations with one solutio...

A parametric equation is defined by a variable t such as y = 4t +1 and x = 2t, while general equation is defined sorely by y and x (in 2 dimensional space). As t is the free variable you can simply replac...

32 out of 80 on a Maths test38% on an English testAs we don't know any other information about the English test (e.g. her mark and the total mark) the only way that we can compare the two...

 a) 3x + 5y =  26  

b) 2x + 2y = 12

Step One: We need to find a way to equate either the x terms of the y terms in each equation. Multiply equation a) by 2 ...