Answer: <u>An atom is the basic unit of matter</u> and the defining structure of elements. The difference between an atom and a molecule is that <u>molecules are formed when two or more atoms bond together</u>. If molecules contain atoms of different elements, that substance is known as a compound. <u>Atoms make up molecules. </u>
Answer:
1) James brother is 10-x years old
2) James was 3 years ago x-3 years old
3) James brother was 3 years ago 7-x years old
4) 3(x-3)=7-x
5) James is 4 years old, his brother is 6 years old
Step-by-step explanation:
3) 10 - x - 3 = 7 - x
5) 3* James age 3 years ago = James brothers age 3 years ago
<=> 3*(x-3) = 7-x
<=> 3x - 9 = 7 - x
<=> 4x = 16
<=> x = 4
Answer:
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M^2 = 49
M^2 = 7^2
M = -7 and M = 7
Answer:
254 cm² (to 3 s.f.)
Step-by-step explanation:
Area of shaded region
= area of large circle -area of smaller circle

Radius of large circle= 15cm
Radius of smaller circle= 12cm
Area of shaded region
= π(15²) -π(12²)
= 225π -144π
= 81π
= 81(3.14)
= 254.34
= 254 cm² (3 s.f.)