The sum of two complementary angles is 90° Angle A is represented by 3x - 10, and Angle B is represented by x. Solve for x Hint: combine the 2 angles and set equal to 90

Angle A = 3x - 10

Angle B = x

Their angle sum = 90° ( complementary angles form 90° )

This can be written in an equation as =

= 3x - 10 + x = 90

= 3x + × + ( -10 ) = 90

= 4x + (-10) = 90

= 4x = 90 + 10 ( transposing-10 from LHS to RHS changes-10 to +10 )

= 4x = 100

= x = 100 ÷ 4 ( transposing ×4 from LHS to RHS changes ×4 to ÷4 )

= x = 25

Angle A = 3x - 10

= 3 × 25 - 10

= 75 - 10

= Angle A = 65°

Angle B = x = 25°

Their sum = 65 + 25 = 90°

Therefore , the complementary angles , Angle A = 65° and Angle B = 25° .

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this