Answer:
9
Step-by-step explanation:
second box is nine because it is half of the 3 x 6 part
a=15
By pythagoras' theorem
25²=20²+a²
625=400+a² group like terms
a²=625-400
a²=225
therefore a=15
no
no. substitute -1 for x and -2 for y.
the first one is -1 - 10
this equals -11 not 3