2. Positive proportion because: product = another factor × a factor.

3. The positive ratio is because the triangle area = (base × height) × 2.

4. Positive proportion because: dividend = divisor × quotient

5. Not proportional, because: distance repaired = total distance-remaining distance.

Summary: involving X method! And no constant term is directly proportional to the multiple term.

100×3/4=75 (the first application problem)

Because the physical city is also proportional to the length of the shadow.

So 5.4×3/2.7=6 meters (second application problem)

5÷2.5=2 2. 15×2=4.3 hectares (the third application problem)

Please tell me if you don't understand.