Charity

Tereza earns 50% more than she spends each month. Patricia earns the same as Teresa but spends 20% less than Teresa. Each of them sends a fifth of the unspent money to the children's home account each month. How much more or less does Patricia send than Teresa?

Correct answer:

p =  20 %

Step-by-step explanation:

$$\begin{gathered} t=10000 \\ {u}_1=t-50/100\cdot t=10000-50/100\cdot 10000=5000 \\ {z}_1=t-u_1=10000-5000=5000 \\ p=t=10000=20 \\ {u}_2=(1-20/100)\cdot u_1=(1-20/100)\cdot 5000=4000 \\ {z}_2=p-u_2=20-4000=6000 \\ {d}_1=z_1/5=5000/5=1000 \\ {d}_2=z_2/5=6000/5=1200 \\ p=(d_2-d_1)/d_1\cdot 100=(1200-1000)/1000\cdot 100=20\% \end{gathered}$$

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