Answer :
The amount of concrete, in tonnes, can she make is 56/5 tonnes
What is proportion?
Proportion can simply be defined as a mathematical comparison that is between two numbers.
Based on proportion, if two sets of given numbers are increasing or decreasing in the same value, then the ratios are identified as being directly proportional to each other.
Proportions are denoted using the symbol "::" or "=".
It is also seen as an equation or statement used to depict that two ratios or fractions are equal.
From the information given, we have that;
3/8 tonnes of sand = 1 tonnes of concrete
Then, 21/5 tonnes of sand = x
cross multiply
x = 21/5 × 8 /3
Divide
x = 56/5 tonnes of concrete
Learn about proportion at: https://brainly.com/question/1781657
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