Solving simultaneous equations quiz with answers. This is an interactive online quiz, the idea is to solve two equations both containing two missing variables at the same time. The first step is to make one value the subject of the formula in one equation and substitute that value in another equation. This topic of algebra focuses on making variables the subject of the formula studied earlier under the topic of linear equations. Learn how to solve simultaneous equations by taking this test and checking the answer key for feedback. The math exercise is for students in 4th, 5th, 6th and 7th grades.