# Is it straight forward?

Algebra Level 5

Given complex numbers $$z_1,z_2$$ satisfying:

• $$|z_1|=5,|z_2|=13$$

• $$39z_1-15z_2=7(4+7i)$$,

If $$z_1z_2=a+bi$$ with real numbers $$a,b$$, find $$2a+b$$

Notation: $$|z|$$ denotes the absolute value of complex number $$z$$.

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