please try to do this.......

Dear Student.

$$\begin{gathered} By angle sum property of quadrilateral. \\ Sum of all the angles of a quadrilateral is 360. \\ thus, a+b+c+70=360 \\ putting the values of b and c. \\ a+2a+15+3a+5+70=360 \\ 6a+90=360 \\ 6a=270 \\ a=45 \\ b=2\times 45+15=105 \\ c=3\times 45+5=140 \end{gathered}$$

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