How do you use cross products to solve `a/24=7/8`?

Related questions

• What is the difference between proportions and ratios?
• What is the difference between ratios and rates?
• What are cross products?
• How do you write "12 meters to 4 floors" as a rate?
• How do you write and simplify "150 boys to 175 girls" as a ratio?
• How do you solve `\frac{6}{19} = \frac{x}{11}`?
• How do you solve `\frac{n+1}{11} = -2`?
• How do you solve `\frac{0.1}{1.01} = \frac{1.9}{x}`?
• How do you use proportions to solve how much money the restaurant made if it serves 250 people...
• How do you solve `x/4-7=13`?