Answer:
240cm²
explanation
Diagonal ²=Length ²+breath ²
26²=10²+length ²
676=100+length ²
576=length ²
length=24cm
Area of a rectangle=length×breath
Area=24×10
=240cm²
Parentheses first
9q-14+3q-3(8)=7
9q-14+3q-24=7
Combine like terms
9q + 3q - 14 - 24 = 7
12q -38=7
add 38 to both sides
12q - 38 + 38 = 7 + 38
12q = 45
divide both sides by 12
q = 45/12
q = 3.75

will contain a minimum of 7 and a maximum of 11 elements. The number depends on how many are in both sets.