Solve the following simultaneous equation: 3x+2y=20 and x+4y=20

We are going to try to eliminate one of the variables in one of the equations. This can be done by rearranging the second equation to x=20-4y. And then substituting x into the first equation.3x+2y=20 => 3*(20-4y)+2y=20 => 60-12y+2y=20 Then we separate constants and variables:=> -10y=-40 => y=(-40)/(-10) => y=4We have found y! Now it's easy to find x, using the equation x=20-4y => x=20-4*4 => x=4So the numbers which satisfy the two equations simultaniously are x=4 and y=4.

SK

Related Maths 13 Plus answers

All answers ▸

Write 240 grams as a fraction of 4kg in its simplest form


Write each of the following numbers to 2 decimal places: 65.4632, 9.8971.


If a = 2.8x10^5 and b=1.6 x 10^6, give the values of i) a +b and ii) a x b


If Tom has a bag of balls with 7 orange, 6 green and 11 blue, what is the probability that he will pick a green ball?