We are given
ABCD is a rhombus
so, firstly , we need to draw diagram
we can see that
diagonal bisects angle
so,
m∠DAB=2*m∠DAC
now, we can plug values
![11x-3=2(4x+9)](https://img.qammunity.org/2019/formulas/mathematics/high-school/pz5c4769rk0wu1fp1w90vtynn6p3hh8hqj.png)
now, we can solve for x
![11x-3=2*4x+2*9](https://img.qammunity.org/2019/formulas/mathematics/high-school/74lszu7txp78opajxdzt1bubyk4le5zhvw.png)
![11x-3=8x+18](https://img.qammunity.org/2019/formulas/mathematics/high-school/nxx666kqqmqo6iks1179edxmujcpx54p6k.png)
![11x-3+3=8x+18+3](https://img.qammunity.org/2019/formulas/mathematics/high-school/8bs3wfejj40sg1sfxga8g3eguhun23ca1y.png)
![11x=8x+21](https://img.qammunity.org/2019/formulas/mathematics/high-school/ib0j2dcd1830nmkmr3xzeg7iq1za47c3x3.png)
subtract both sides by 8x
![11x-8x=8x-8x+21](https://img.qammunity.org/2019/formulas/mathematics/high-school/nylkwuidzdgtbqehgmjvzwd1ddt158zrrt.png)
![3x=21](https://img.qammunity.org/2019/formulas/mathematics/middle-school/jubpjsh8lyn020kfz85hbtgl4p78ymr33f.png)
Divide both sides by 3
we get
...............Answer