Question

What is the value of x?

20

40

45

85

Answer 1

Complementary angles have sum 90°

$\\ \sf\longmapsto 2x+10=90$

$\\ \sf\longmapsto 2x=90-10$

$\\ \sf\longmapsto 2x=80$

$\\ \sf\longmapsto x=40$