Question

When to cross multiply and when to multiply across?

Answer 1

Answer:

Multiply the top and bottom of the first fraction by the bottom number of the second fraction.

Multiply the top and bottom of the first fraction by the bottom number of the second fraction.8 × 312 × 3 = 23

Multiply the top and bottom of the first fraction by the bottom number of the second fraction.8 × 312 × 3 = 23Step 2: Multiply the top and bottom of the second fraction by the bottom number that the first fraction had.

Multiply the top and bottom of the first fraction by the bottom number of the second fraction.8 × 312 × 3 = 23Step 2: Multiply the top and bottom of the second fraction by the bottom number that the first fraction had.8 × 312 × 3 = 2 × 123 × 12

Multiply the top and bottom of the first fraction by the bottom number of the second fraction.8 × 312 × 3 = 23Step 2: Multiply the top and bottom of the second fraction by the bottom number that the first fraction had.8 × 312 × 3 = 2 × 123 × 12And Magic! The bottom of both fractions is now 12 × 3

Multiply the top and bottom of the first fraction by the bottom number of the second fraction.8 × 312 × 3 = 23Step 2: Multiply the top and bottom of the second fraction by the bottom number that the first fraction had.8 × 312 × 3 = 2 × 123 × 12And Magic! The bottom of both fractions is now 12 × 3Step 3: We can get rid of the 12 × 3 (as we are dividing both sides by the same amount) and the equation is still true:

Multiply the top and bottom of the first fraction by the bottom number of the second fraction.8 × 312 × 3 = 23Step 2: Multiply the top and bottom of the second fraction by the bottom number that the first fraction had.8 × 312 × 3 = 2 × 123 × 12And Magic! The bottom of both fractions is now 12 × 3Step 3: We can get rid of the 12 × 3 (as we are dividing both sides by the same amount) and the equation is still true:8 × 3 = 12 × 2