A yard holds only bicycles and tricycles. There are 10 cycles in total and 23 wheels. How many tricycles are there?

1. Give the unknowns letters: let b be the number of bicycles and t the number of tricycles. 2. The first fact is that the cycles number 10 in total, so b plus t equals 10. 3. A bicycle has two wheels and a tricycle has three wheels. 4. The second fact is that the wheels number 23, so two b plus three t equals 23. 5. From the first equation, b equals 10 minus t. 6. Substituting gives two times 10 minus t, plus three t, equal to 23. 7. That simplifies to 20 plus t equal to 23, so t equals 3. 8. Check the answer: 7 bicycles give 14 wheels and 3 tricycles give 9 wheels, and 14 plus 9 is 23. _Source: Siyavula Mathematics Grade 10 (Everything Maths, CC BY 4.0), Chapter 4: Equations and inequalities_