Please help me solve this % numerical chemistry problem

[Ifrah tahir]

Homework Statement

150g of a solution which is 20% sulphuric acid (by mass) are added to x grams of a solution which is 70% sulphuric acid (by mass). What must be the value of x so that the final mixture shall contain 30% sulphuric acid (by mass)?

Relevant Equations

None

I've tried both c1v1 and unitary method but couldn't solve

 

[haruspex]

Homework Statement:: 150g of a solution which is 20% sulphuric acid (by mass) are added to x grams of a solution which is 70% sulphuric acid (by mass). What must be the value of x so that the final mixture shall contain 30% sulphuric acid (by mass)?
Relevant Equations:: None

I've tried both c1v1 and unitary method but couldn't solve

Your attempt is just a lot of numbers. Please provide your reasoning.
Take the trouble to type in your work. Images are just for diagrams and printed text.

 

[Cutter Ketch]

Also, there is a way to make your smart phone camera focus.