hello!
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First of all, let the number be u.
The product of 7 and u means you should multiply 7 times u:
![\pmb{7u}](https://img.qammunity.org/2023/formulas/mathematics/college/mlegse29iikwngcaq9nkrcfl98xzmjf68i.png)
Now, subtract 4:
![\pmb{7u-4}](https://img.qammunity.org/2023/formulas/mathematics/college/uwfupvcx084nm9anwsbawuv448oycpk3e2.png)
This expression equals 17:
![\pmb{7u-4=17}](https://img.qammunity.org/2023/formulas/mathematics/college/xlf83957eg47q1dy1shkbjjyxpwylakq1s.png)
![\rule{200}{2}](https://img.qammunity.org/2023/formulas/mathematics/high-school/2ko50n2a94ze3uv7co8x4970xhxkhutpe8.png)
[Now, let's Find the Value of u]
First, add 4 to both sides:
![\pmb{7u=21}](https://img.qammunity.org/2023/formulas/mathematics/college/8md9g6ypw6ojzw39bwgg2q25q4wpy9txd3.png)
Now, divide both sides by 7:
![\pmb{u=3}](https://img.qammunity.org/2023/formulas/mathematics/college/buqbiyuttz7qsqczmgwvq7cwy9qs5tu4k0.png)
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notes:-
Hope everything is clear; if you need any clarification /explanation, kindly let me know, and I will comment and/or edit my answer :)